The disclosure herein relates generally to an imaging apparatus and fuser components thereof for use in electrophotographic, including digital, image-on-image, and like apparatuses. The fuser members are useful for many purposes including fixing a toner image to a copy substrate. More specifically, the disclosure relates to fuser components comprising an outer layer comprising a fluorinated polyimide. In embodiments, the fluorinated polyimide is crosslinked. In embodiments, the fluorinated polyimide outer layer is positioned on a substrate, which may be of many configurations including a roller, belt, film, or like substrate. In embodiments, there is positioned between the substrate and the outer layer, an intermediate and/or adhesive layer. In embodiments, the fusing system is oil-less, thereby eliminating the need for a release oil, release agent, fuser oil, or the like. The fuser members may be useful in xerographic machines, such as copiers, printers, facsimiles, multifunction machines, and including color machines.
In a typical electrophotographic reproducing apparatus, a light image of an original to be copied is recorded in the form of an electrostatic latent image upon a photosensitive member and the latent image is subsequently rendered visible by the application of electroscopic thermoplastic resin particles which are commonly referred to as toner. The visible toner image is then in a loose powdered form and can be easily disturbed or destroyed. The toner image is usually fixed or fused upon a support, which may be the photosensitive member itself, or other support sheet such as plain paper.
The use of thermal energy for fixing toner images onto a support member is well known and methods include providing the application of heat and pressure substantially concurrently by various means: a roll pair maintained in pressure contact, a belt member in pressure contact with a roll, a belt member in pressure contact with a heater, and the like. Heat may be applied by heating one or both of the rolls, plate members, or belt members. With a fixing apparatus using a thin film in pressure contact with a heater, the electric power consumption is small, and the warming-up period is significantly reduced or eliminated.
It is desired in the fusing process that minimal or no offset of the toner particles from the support to the fuser member take place during normal operations. Toner particles offset onto the fuser member may subsequently transfer to other parts of the machine or onto the support in subsequent copying cycles, thus increasing the background or interfering with the material being copied there. The referred to “hot offset” occurs when the temperature of the toner is increased to a point where the toner particles liquefy and a splitting of the molten toner takes place during the fusing operation with a portion remaining on the fuser member. The hot offset temperature or degradation of the hot offset temperature is a measure of the release property of the fuser, and accordingly, it is desired to provide a fusing surface which has a low surface energy to provide the necessary release. To ensure and maintain good release properties of the fuser, it has become customary to apply release agents to the fuser roll during the fusing operation. Typically, these materials are applied as thin films of, for example, silicone oils to prevent toner offset.
Another method for reducing offset, is to impart antistatic and/or field assisted toner transfer properties to the fuser. However, to control the electrical conductivity of the release layer, the conformability and low surface energy properties of the release layer are often affected.
With a focus on oil-less fusing, energy-efficiency, and fast warm-up time (e.g., inductive heated fuser), belt fusing configuration and reliability/productivity is currently achieved by increased fuser belt size and additional system approaches. There are only a few material solutions that meet the current high demands for fusing, especially for oil-less fusing. Two major material choices include PFA/PTFE for oil-less fusing, and VITON-GF® (DuPont) fluoroelastomers used in combination with oil systems for high end production. Addition of fillers to improve mechanical properties and thermal conductivity is a general trend for life improvement.
PFA represents a type of fluoroplastic, which currently is the only practical material choice for oil-less fusing. However, the downside to using this material includes a resulting mechanically rigid material that is easily damaged by denting or from extensive turning. Also, PFA is difficult to process and there is limited room for material modification. Also, PFA requires high curing temperatures if known coating methods are used.
Turning to VITON®, this material is one of the most popular fluoroelastomers for fusing, as it is mechanically flexible, and less damage results due to its capability to absorb shock energy. The material requires low curing temperatures and has wide material modification latitude. However, this fluoroelastomer requires oil for release due to the low fluorine content of the material.
While the above polymers have desirable properties such as thermal and chemical stability and low surface-energy, fuser members using these materials continue to fail at shorter times than is desirable, primarily due to wear and poor release at the surface (offset).
A new material system for fusing is desired that exhibits improved wear and release properties without requiring the addition of a release fluid (oil-free). In addition, there is a desire to provide an outer layer fusing material that is tunable to enable superior fusing performance with less system parts, and that requires less time for manufacture.